Meaning
A plain, solid red circle. On its own it means red, stop, alert or a status dot showing something is live, busy or important.
It is the classic marker for live broadcasts and recordings, and it works as a strong bullet or a way to flag urgent items: “🔴 LIVE now, come say hi” Teams and sides are often shown as 🔴 against 🔵. For a softer status, 🟡 or 🟢 signal away or available.